1. Field of the Invention
The present invention relates to a tubular connector used to connect first and second fluid tubes, for an example, one suitably applicable to a blood pumping device for artificial heart.
2. Description of the Prior Art
In recent years, increasing effort has been expended in the development of artificial heart devices including those used paracorporeally in heart and other operations to assist and temporarily substitute the heart in its function. For example, as illustrated in FIG. 1, a pair of units of sac type blood pumping device 11 are connected, one between the right atrium of heart 10 and pulmonary artery and the other between the left atrium and aorta. Also in Japan, one of the leading countries in this field of technology, such a blood pumping device has been studied, and is already clinically applied as the temporary assist heart.
As explicitly illustrated in FIG. 2, this sac type blood pumping device 11 is composed of two major components, a pressure resistant housing outer case 1, for example, made of polycarbonate or polyurethane resin and a flat sac 2 that is housed airtight inside the above housing outer case to provide a blood chamber. On top of this flat sac 2, a blood inlet port 3 and a blood outlet port 4 are formed, rising upward almost in parallel to each other, to provide passages to and from the inside space of blood chamber. A flange 5 is provided around the circumference of the top of sac 2 to form part of the housing. This flange airtightly closes the sac 2 in the housing outer case 1. Further, as illustrated in FIGS. 3 and 4, the blood inlet port 3 and blood outlet port 4 are fitted inside with artificial check valves 6 and 7, respectively, on individual annular valve seats 20 so that the backflow of blood 17 may be prevented. Under the operation of these valves, blood 17 is introduced through the blood inlet port 3 into the sac 2 and pumped out pulsatively through the blood outlet port 4. For such pulsatile pumping of blood, a fluid, for example, air is alternately introduced from a compressed air source and sucked out under vacuumed pressure through a single port 8 provided at the bottom of housing outer case 1 so that as the outer pressure of sac 2 changes, the sac may swell and contract repeatedly. Cannulae 12, from a heart or a blood vessel, are connected to one side of individual connectors 13 while blood inlet ports 3 and blood outlet ports 4 on sacs 2 are connected to the other side thereof by fitting these cannulae and ports to the connectors until they are stopped by annular flanges 14 provided halfway between both ends of the connectors.
With the blood pumping device 11 as mentioned above, since the check valves 6 and 7 are built in the blood inlet port 3 and blood outlet port 4, respectively, it is necessary to have a sufficient dimensional accuracy at the built-in position of the valves. Namely, the inside surface of the blood inlet and outlet ports 3 and 4 must be finished to dimensions accurate enough for individual valve seats 20 for valves 6 and 7 to sit tight inside (on an annular swelling). For this end, molding requires an accurate core mold. Further, the construction, that the ports 3 and 4 to be fitted with a built-in valve are integrally formed with the sac 2 to be housed inside the pumping device 11, is very difficult to mold by a single step process because of the shape of the sac. This means multiple molding steps and therefore very often means a higher molding cost.
It is noted that since the connectors 13 as mentioned above are shaped as shown and are rigid it will be very difficult to alleviate the above problem by building the valves 6 or 7 in the connectors.